Another 3 inches with a tit fuck!

So I am lucky to be married to a very busty wife (34/36 G/F cup), and we have been married for about 5 years now. When we first got married, I was about 6 1/2 inches long. I can say when we first got married, we had not done a lot of fooling around because we wanted to wait. We both had a previous experience but wanted this to be special. I of course started to get some tit fuck action once we got married though. I loved it. Then we got away from doing that for some reason. For about 3 years. Then a few weeks ago, we saw a show on TV and their was a girl with very big tits, and we wanted to tit fuck again. This time though, she was able to suck the end of my cock while tit fucking. We weren't able to do that before. We measured my dick and I am now about 9 1/2 inches long. In the last 3 to 4 years, my length has grown. I have never heard of this, but am not complaining. Does ones penis get bigger with lots of sex? We have had a very healthy sex life and hadn't really noticed until now.